Field of Invention
This invention relates generally to devices usable in surgical procedures to illuminate a region of interest, and more particularly to a disposable clip-on light pipe illumination assembly in which the front section of the light pipe which projects into the surgical site is orientable to illuminate any region of interest to the surgeon.
Though the invention will be described mainly in the context of surgical applications, it is to be understood that the invention is not limited thereto, for an assembly in accordance with the invention is capable of transmitting light of high intensity by means of an orientable light pipe to remote or inaccessible work sites which are difficult to illuminate by conventional techniques.
The professional concern of doctors and surgeons is with body cavities and surgical sites which, unless clearly visible, cannot be properly diagnosed or treated. Existing techniques for illuminating such regions are often inadequate and unsafe, for they either do not succeed in supplying sufficient illumination or they generate excessive amounts of heat which may injure human tissue as well as cause discomfort to the observer. In some instances, commercially available illuminators interfere with medical procedures and also constitute a hazard to both patient and doctor.
The standard operating room illuminator is constituted by batteries of explosion-proof spot lamps and floor lamps, which are capable of being shifted or aimed to suit particular procedures. Such illuminators, which are quite costly, are not only cumbersome, but they fail to afford adequate illumination for deep cavities, in that the light sources are above or behind the surgeons or other operating personnel, whose heads, hands and instruments, as they shift position, often block the light rays.
In recent years, attempts have been made to use long, flexible fiber optics light guides in medical and related applications. Such guides are advantageous in that they furnish "cold light" and segregate the heavy and bulky assembly of lamp, condenser and cooling system from the point of observation. Also, with the development of flexible fiber optic guides with fused ends and plastic casings, sterilization of the instrument is possible.
In its preferred form, a clip-on assembly in accordance with the present invention includes a flexible light guide in a monofilament-core pipe format. This represents a particular species of an optical fiber. It is important, therefore, that the distinctions which exist between a conventional multi-fiber optical light pipe or cable and a light pipe having a monofilament-core be clearly understood.
An optical fiber is a dielectric waveguide structure which functions by internal reflection to confine and guide light. It consists of an inner dielectric material, called the core, surrounded by another dielectric material having a smaller refractive index, referred to as the cladding. Currently, all optical fibers in general use have a cylindrical circular cross section.
The amount of light flux which an optical fiber is capable of conveying depends on the cross-sectional diameter of the core; and when there is a need to transmit large amounts of light at a constant level for purposes of illumination, rather than a modulated light signal for purposes of communication, use is usually made of a bunched cluster of optical fibers, each conveying a small amount of light.
Since the present invention is concerned primarily with illumination, it employs a light guide in the form of a flexible pipe having a monofilament-core of large diameter surrounded by a cladding tube. The monofilament core serves the same function as a cluster of small diameter cores, but operates with far greater optical efficiency to transmit large amounts of light with minimal transmission losses. It is also more bendable than conventional multi-filament core light pipes.
Fiber optic guides may be used as auxiliary illuminators for close diagnostic and surgical operations, as illuminators for direct or indirect ophthalmoscopes, and as specially shaped illumination accessories to classical-designed cytoscopes, proctoscopes, retractors, and various forms of medical, surgical and dental tools.
Despite the obvious advantages of fiber optics for cold-light illumination, their use in the surgical, medical and dental fields has been relatively limited. The reason for such limited use does not lie in any inherent theoretical deficiency, but in the fact that with existing technology, the three basic components of the fiber optics system, when brought together, do not afford sufficient illumination in those situations calling for large amounts of cold light which can be readily directed to selected regions of a body cavity.
In our copending patent application, above-identified, a medical instrument and light pipe assembly is disclosed which makes use of a flexible plastic light pipe whose monofilament core is surrounded by a cladding tube, the light pipe being joined to an instrument such as a surgical retractor which, when put to use, assumes a position in which its operative blade lies adjacent to the field of interest, such as a body cavity or surgical site.
The optical inlet at the rear end of the light pipe is coupled to a light source whereby light transmitted by the pipe is discharged from an optical outlet at the front section of the pipe which is adjacent to the blade of the retractor. The front section of the pipe is sheathed in a bendable neck having dead soft characteristics whereby the user, by bending the neck, may so orient the optical outlet as to direct the light toward a desired region of the surgical site.
In the assembly disclosed in our copending application, the specially-designed molded plastic retractor included in the assembly is provided with clips or other routing means to link the retractor to the flexible light pipe; hence standard retractors cannot be used for this purpose.
Most hospital facilities carry a large inventory of standard retractors of different types, and these are often put to use in surgical procedures. Though distinct advantages may be gained by replacing standard retractors with the specially-designed retractors disclosed in our copending application, which are combined with orientable light pipe illuminators, practical considerations dictate the need for an independent device capable of exploiting these orientable illuminators for use in conjunction with standard surgical retractors.
In this way, surgeons can continue to carry out procedures with available retractors and other conventional instruments and yet take advantage of the enhanced and unobstructed illumination afforded by spilling light directly onto the surgical site, rather than drawing light from overhead sources which may be more or less occluded by personnel working in the vicinity of the surgical site.
The prior art patent of greatest interest is the Reick-Wilder Pat. No. 3,641,332, which discloses a flexible light pipe constituted by a monofilament core of resinous material of large diameter, such as methyl methacrylate contained within a cladding tube formed of FEP (Teflon), the core being separated from the tube by a film of air. The core has a relatively high index of refraction capable of transmitting light by internal reflectors, whereas the cladding tube has a relatively low refractive index.